Sorting device separating a powder mixture into spheroidal and sharp-edged particles

ABSTRACT

Sorting device for the separation of a powder mixture into spheroidal particles and sharp-edged particles. The device comprises an inclined cascade-sorting channel or tunnel, a vibrating chute above the upper end of the channel or tunnel and receiving means collecting spheroidal and sharp-edged particles, respectively, the said means being placed below the lower end of the channel or tunnel. The cascade-sorting channel or tunnel comprises more particularly an elongated container, which has an inlet disposed at its upper end and has outlets disposed at its lower end. A plurality of separating cascade members, which have a length l, are spaced apart at intervals a, are disposed at different levels at separations h and are inclined at an angle Beta , with respect to the horizontal, are secured to the side walls of the container, and a separating plate is positioned near the lower end of the container.

United States Patent Schwartz et al.

SORTING DEVICE SEPARATING A POWDER MIXTURE INTO SPHEROIDAL AND SHARP-EDGED PARTICLES Inventors: Giinther Schwartz, I-lurth-Gleuel;

Klaus Frank, Hurth-l-lermulheim, both of Germany Assignee: I-Ioechst Aktiengesellschaft,

Frankfurt, Germany Filed: Oct. 29, 1973 Appl. No.: 410,686

[30] Foreign Application Priority Data Oct. 31, 1972 Germany 2253353 [52] US. Cl. 209/118 [51] Int. Cl B07b 13/10 [58] Field of Search 209/73, 115, 117, 118

[56] References Cited UNITED STATES PATENTS 171,502 12/1875 Catchpole et a1 209/115 773,928 11/1904 Colvin 209/115 [451 Aug. 12, 1975 2,549,316 4/1951 Kramer et al 209/97 Primary ExaminerAllen N. Knowles Attorney, Agent, or FirmConnolly and Hutz [57 ABSTRACT Sorting device for the separation of a powder mixture into spheroidal particles and sharp-edged particles. The device comprises an inclined cascade-sorting channel or tunnel, a vibrating chute above the upper end of the channel or tunnel and receiving means collecting spheroidal and sharp-edged particles, respectively, the said means being placed below the lower end of the channel or tunnel. The cascade-sorting channel or tunnel comprises more particularly an elongated container, which has an inlet disposed at its upper end and has outlets disposed at its lower end. A plurality of separating cascade members, which have a length l, are spaced apart at intervals 11, are disposed at different levels at separations h and are inclined at an angle B, with respect to the horizontal, are secured to the side walls of the container, and a separating 11 Claims, 2 Drawing Figures SORTING DEVICE SEPARATINGIA MIXTURE INTO SPHEROIDAL AND SHARP-EDGED PARTICLES The present invention relates to a sorting device adapted to separate a powder blend into spheroidal particles and sharp-edged particles.

It is known that the utility of metal powders greatly depends on the shapes and the surface configurations of the individual powder particles. In powder metallurgy, it is appropriate to use irregularly shaped sharpedged particles so as to obtain articles of good mechanical strength, even if unsintered. Spheroidal particles in turn are appropriate in, for example, cutting operations employing pulverulent material, or again in the production of metal filters, where good flow behaviour and/or uniform and relatively large pores are an important requirement.

In some cases, especially in the atomization of a melt, it is possible to produce powder consisting of either spheroidal particles or sharp-edged particles by the selection of appropriate working conditions, including temperature, chemical composition of the melt, atomization-inducing means, and nozzle configuration.

Attempts have also been made to produce regularlyshaped powder particles by subjecting the powder to an after-treatment. As disclosed in German published specification (Offenlegungsschrift) No. 2,107,947, irregularly shaped particles are melted so as to become round in a plasma jet. Finally, it is possible for metal powders consisting of variously shaped particles to be separated mechanically into spheroidal particles and sharp-edged particles. To this end, use can be made of devices including a vibrating chute or a rotating plate (cf. Stahl und Eisen 84, 1964, pages 737 and 738).

These devices are not fully satisfactory, however, as they merely enable particles widely different in shape to be reliably separated. In those cases in which the particles include intermediate grade material, the separation ceases to be reliable, and it is necessary for the fractions of spheroidal particles and sharp-edged particles initially obtained to be treated once again in the same way, naturally with the expenditure of time necessary therefor. It should be added that it is basically necessary for the powder to be classified into individual sieve fractions, prior to effecting the separation vin a known separator. This is not difficult to achieve, but it entails additional work.

It is accordingly an object of the present invention to provide a fully satisfactory sorting device for the separation of a powder blend into spheroidal particles and sharp-edged particles, and more particularly for the reliable separation of a metal powder into spheroidal particle and sharp-edged particle fractions, each fraction containing merely minor proportions of the particles intended for the other fraction, independently of the particles shape and sieve analysis.

According to the present invention, we provide a sorting device for the separation of a powder mixture into spheroidal particles and sharp-edged particles, comprising an inclined cascade-sorting channel or tunnel, a vibrating chute positioned above the upper end of the cascade-sorting channel or tunnel and receiving means collecting spheroidal particles and sharp-edged particles, respectively, the receiving means being placed below the lower end. of the cascade-sorting channel or tunnel.

Preferred features of the present invention, which can be adopted singly or in combination, provide for: a. the cascade sorting channel or tunnel to comprise an elongated container, which has an inlet disposed at its upper end and has outlets disposed at its lower end; for a plurality of separating cascade members having a length 1 to be secured to the side walls of the container, to be spaced apart at intervals a, to be disposed at different levels at separations h, and to be inclined under an angle ,8 with respect to the horizontal; and for a separating plate to be positioned near the lower end of the container.

b. for a braking apron to be secured above each of the separating cascade members, at the upstream end thereof;

c. for the container to be carried by a supporting frame which affords an inclined supporting plane;

(I. for the angle of inclination at of the inclined supporting plane to be adjusted by means of a prop which has a series of apertures spaced along its length and pivoted on a horizontal member of the supporting frame;

e. for the angle of inclination a to comprise an angle between 10 and 50, preferably between 15 and 30, with respect to the horizontal;

f. for the angle B to comprise an angle between 3 and 20, preferably between 4 and 8, with respect to the horizontal;

g. for a ratio between (0.5 l) (0.5 l) (7 25) to be selected for the intervals a, the height h of the separating cascade members and their length l;

h. for a plurality of vibrators and shock absorbers to be interposed between the cascade-sorting channel or tunnel and the supporting frame;

i. for a feed funnel to be mounted above the magnetic gutter.

In the sorting device of the present invention, advantage is taken of the fact that spheroidal material placed on an inclined plane begins to move forward by rolling, at a certain velocity, under the action of gravity, whereas irregularly shaped particles commence moving forward by sliding, again at a certain velocity; however, the rolling velocity is always faster than the sliding velocity. As a result, it is possible for the spheroidal particles to clear slit-like gaps which are disposed at right angles to their direction of motion, whereas the sharpedged particles will drop thereinto.

In order to improve the separation efficiency of the sorting device, it is possible for a plurality of slit-like gaps to be arranged one after the other so as to form a cascade, the separating efficiency being the greater, the greater the number of gaps.

Still further, it is possible to obtain an additional improvement in the separation efficiency by the provision of braking aprons disposed above each separating cascade member and downstream of each slit-like gap; these braking aprons make it possible to inhibit the possible carrying along of sharp-edged particles with the spheroidal particles (this may be liable to occur more especially in those cases in which the cascade sorting channel or tunnel is supplied with considerable quantities of powder). Under the action of gravity, the two grades of particles decelerated by the braking aprons commence moving again towards the next separating cascade member. In the absence of braking aprons which effect deceleration as just indicated, it is possible that spheroidal particles and sharp-edged particles will both clear a number of the gaps provided between the separating cascade members, which is undesirable as sharp-edged particles may thereby find their way into the receptacle intended to receive spheroidal particles.

The angle of inclination B selected for the separating cascade members, and the width of the gaps provided therebetween, can have any values compatible with the requirements of the separation operation in question.

More particularly, however, it may be stated that it is appropriate for the angle of inclination B to be decreased for an increasing diameter of the powder particles, and for the gaps to be made wider.

By means of one or more vibrators, an oscillatory motion can be imparted to the cascade sorting channel or tunnel. This is to be recommended inasmuch as it can prevent sharp-edged particles from lying still on the bottom of the cascade sorting channel or tunnel, and inasmuch as it can promote a regular distribution of the material travelling thereover.

Use can be made of the sorting device of the present invention even for separating particles which are widely different in size.

An exemplifying embodiment of the apparatus of the present invention is shown diagrammatically, partially in section, in the accompanying drawing, wherein FIG. 1 is a side view of the sorting device along line l- 1 of FIG. 2; and A FIG. 2 is a top view of the sorting device.

As can be seen from the drawing, a vibrating chute 2, which has a feed funnel 3 mounted thereabove, is positioned above an inlet 4 opening into an elongated container 7 provided with outlets 12 and 13. The container 7, the inlet 4, and the outlets l2 and 13, which are adapted to deliver spheroidal and sharp-edged particles, respectively, and also a lower separating plate 6 and separating cascade members 5, which are secured to the side walls of the container 7, and in addition braking aprons 16, which are secured above the separating cascade members 5, are so disposed as to form a cascade-sorting tunnel l. The separating cascade members are inclined with respect to the horizontal at an angle ,8 which may suitably be between 3 and Placed below the cascade-sorting tunnel 1 is a supporting frame 14, which affords an inclined supporting plane, disposed at an angle a which may suitably be between and 50 with respect to the horizontal. The angle a can be adjusted by means of a prop 15, which has a series of apertures spaced along its length and which is pivoted on the horizontal member of the supporting frame 14. lnterposed between the supporting frame 14 and the container 7, which may be regarded as the housing of the cascade-sorting tunnel 1, there are vibrators 8 and shock absorbers 9 which enable the cascade-sorting tunnel l to be set in oscillatory motion at right angles to the direction of flow of the particles.

Placed below the outlets 12 and 13 there are receptacles 10 and 11 which are intended to receive spheroidal and sharp-edged particles respectively.

The following Examples are intended further to illustrate the sorting device of the present invention.

EXAMPLE 1 A cascade-sorting tunnel 1,000 mm wide and com prising ten separating cascade members 5 and nine braking aprons 16 was used. The separating cascade members 5 were spaced apart at intervals a of 10 mm,

disposed at differentlevels at separations I1 of 20 mm, and had a length I! of mm; the separating cascade members 5 were inclined at an angle ,8 of 4, and the supporting frame 14 was inclined at an angle a of 21.8".

The sorting device was fed with 100 kg per hour of steel particles having sizes between 0.1 and 0.6 mm. The particles comprised 50% of spheroidal material, 20% sharp-edged material and 30% of material of an intermediate grade.

After being passed through the cascade-sorting tunnel, 48.2 kg of these particles were taken from receptacle 10 as the final product; 98.8% of this was spheroidal material and the remaining 1.2% 058 kg) was intermediate grade material.

Receptacle 11 was found to contain 51.8 kg of final product, of which 95.2% consisted of sharp-edged particles and intermediate grade material. The remaining 4.8% 2.4 kg) consisted of spheroidal particles.

EXAMPLE 2 The same sorting device was used as in Example 1, except that the supporting frame 14 was inclined at a slightly smaller angle a of l9.7. The device was fed with 500 kg per hour of steel particles with sizes between 0.9 and 1.3 mm, of which 54.8% was spheroidal material, 19.2% was sharp-edged material and 26% was intermediate grade material.

Receptacle 10 was found to contain 355 kg of final product, of which 12.5% (-42 kg) was intermediate grade material and 7% (=22 kg) consisted of sharpedged particles.

Receptacle 11 contained kg of final product, of which 1.1% (*3 kg) consisted of spheroidal particles.

EXAMPLE 3 A cascade-sorting tunnel 240 mm wide and comprising 10 separating cascade members 5 and nine braking aprons 16 was used. The separating cascade members were spaced apart at intervals a of 5 mm, were disposed at different levels at separations I1 of 7 mm, and had a length l of 100 mm; the separating cascade members 5 were inclined at an angle B of 8, and the supporting frame 14 was inclined at an angle a of 25.

The sorting device was fed with 10 kg per hour of steel particles having sizes between 0.05 and 0.2 mm, of which 75% was spheroidal material, 3% was sharpedged material and 22% was intermediate grade material.

Receptacle 10 was found to contain 7.2 kg of final product, of which more than 99% consisted of spheroidal particles and less than 1% of intermediate grade material.

Receptacle 11 contained 2.8 kg of final product of which 89.2% consisted of sharp-edged particles and intermediate grade material, and 10.8% 0.3 kg) consisted of spheroidal particles.

We claim:

1. A sorting device for separating a powder into spheroidal particles and sharp-edged particles, wherein a plurality of separating cascade members are spaced apart, are disposed at successively lower levels and are inclined with respect to the horizontal so as to form an inclined cascade-sorting tunnel, and are secured to the side walls of an elongated container having an inlet disposed at its upper end and outlets disposed at its lower end; the sorting device comprising braking aprons secured above the separating-cascade members to form interposed between the container and the frame, and

the braking aprons being disposed over the spaces between the cascade members.

2. The sorting device as claimed in claim 1, wherein the angle of inclination a of the inclined supporting plane can be adjusted by means of a prop which has a series of apertures spaced along its length and which is pivoted on a horizontal member of the supporting frame.

3. The sorting device as claimed in claim 1, wherein the angle of inclination 04 comprises an angle between and 50.

4. The sorting device as claimed in claim 3, wherein the angle of inclination 01 comprises an angle between l5 and 30.

5. The sorting device as claimed in claim 1, wherein the angle [3 comprises an angle between 3 and 20.

6. The sorting device as claimed in claim 5, wherein the angle ,8 comprises an angle between 4 and 8.

7. The sorting device as claimed in claim 1, wherein the members have a length I spaced apart at intervals a and are disposed at different levels at a vertical separation h from each other, and, a ratio between (0.5 l) (0.5 l) (7 25) is selected for the intervals a, the height h of the separating cascade members and their length I.

8. The sorting device as claimed in claim 1, wherein a feed funnel is mounted above the vibrating chute.

9. A sorting device as set forth in claim 1, wherein the separating cascade members are inclined backwardly at an angle B of between about 4 and 8 with respect to the horizontal.

10. A sorting device as set forth in claim 1, wherein the braking aprons have a convex surface disposed over cade members to lower cascade members. 

1. A SORTING DEVICE FOR SEPARATING A POWDER INTO SPHEROIDAL PARTICLES AND SHARP-EDGED PARTICLES, WHEREIN A PLURALITY OF SEPARATING CASCADE MEMBERS ARE SPACED APART, ARE DISPOSED AT SUCCESSIVELY LOWER LEVELS AND ARE INCLINED WITH RESPECT TO THE HORIZONTAL SO AS TO FORM AN INCLINED CASCADE-SORTING TUNNEL, AND ARE SECURED TO THE SIDE WALLS OF AN ELONGATED CONTAINER HAVING A INLET DISPOSED AS ITS UPPER END AND OUTLETS DISPOSED AS ITS LOWER END, THE SORTING DEVICE COMPRISING BRAKING APRONS SECURED ABOVE THE SEPARATING-CASCADE MEMBERS TO FORM PART OF THE SORTING TUNNEL, A SEPARATION PLATE BEING POSITIONED NEAR THE LOWER END OF THE ELONGATED CONTAINER, RECEIVING MEANS COLLECTING SPHEROIDAL PARTICLES AND SHARP-EDGED PARTICLES, RESPECTIVELY, THE RECEIVING MEANS BEING PLACED BELOW THE LOWER END OF SAID CONTAINER ON BOTH SIDES OF THE SEPARATION PLATE, A VIBRATING CHUTE POSITIONED ABOVE THE UPPER END OF THE CASCADE-SORTING TUNNEL, A FRAME SUPPORTING THE CONTAINER, THE FRAME PROVIDING A DOWNWARDLY INCLINED SUPPORTING PLANE HAVING AN ANGLE A WITH A RESPECT TO THE HORIZONTAL, A PLURALITY OF VIBRATORS AND SHOCK ABSORBERS BEING INTERPOSED BETWEEN THE CONTAINER AND THE FRAME, AND THE BRAKING APRONS BEING DISPOSED OVER THE SPACES BETWEEN THE CASCADE MEMBERS.
 2. The sorting device as claimed in claim 1, wherein the angle of inclination Alpha of the inclined supporting plane can be adjusted by means of a prop which has a series of apertures spaced along its length and which is pivoted on a horizontal member of the supporting frame.
 3. The sorting device as claimed in claim 1, wherein the angle of inclination Alpha comprises an angle between 10* and 50* .
 4. The sorting device as claimed in claim 3, wherein the angle of inclination Alpha comprises an angle between 15* and 30* .
 5. The sorting device as claimed in claim 1, wherein the angle Beta comprises an angle between 3* and 20* .
 6. The sorting device as claimed in claim 5, wherein the angle Beta comprises an angle between 4* and 8* .
 7. The sorting device as claimed in claim 1, wherein the members have a length l spaced apart at intervals a and are disposed at different levels at a vertical separation h from each other, and, a ratio between (0.5 - 1) : (0.5 - 1) : (7 - 25) is selected for the intervals a, the height h of the separating cascade members and their length l.
 8. The sorting device as claimed in claim 1, wherein a feed funnel is mounted above the vibrating chute.
 9. A sorting device as set forth in claim 1, wherein the separating cascade members are inclined backwardly at an angle Beta of between about 4* and 8* with respect to the horizontal.
 10. A sorting device as set forth in claim 1, wherein the braking aprons have a convex surface disposed over the spaces.
 11. A sorting device as set forth in claim 1, wherein the braking aprons slope downwardly from the adjacent upper cascade member toward the adjacent lower cascade member for directing particles from upper cascade members to lower cascade members. 